… know that it is usually very tedious and that proper recording of binlog file/binlog position needs to be done with care… number of records from the t table s1> select count(*) from t; +———-+ | count(*) | +———-+ | 2 | +———-+ Great! So again, using GTIDs avoids the tedious work of…
Post: ZFS on Linux and MySQL
May 24, 2013 By 17 Comments
… with hundreds of snapshots. With LVM, your IO performance drops to 33% after the first snapshot so keeping a large number of snapshots… mode works well. The tpcc database, which contains a lot of random data that doesn’t compress well showed a compression… ZFS each record on disk has a checksum. If a cosmic ray flip a bit on a drive, instead of crashing InnoDB…
Post: Percona Server 5.1.69-14.7 now available: A drop in replacement for MySQL
June 10, 2013 By 3 Comments
… libmysqlclient18 package was chosen from the distribution’s repository instead of Percona’s which could lead to package conflicts. Bug fixed…. The log tracker thread was unaware of the situation when the oldest untracked log records are overwritten by the new log data… bug #69379 which caused MySQL clients to return bogus error number for host-not-found errors on Ubuntu 13.04. Bug…
Post: MySQL Query Patterns, Optimized - Webinar questions followup
June 3, 2013 By 2 Comments
… you missed it, you can still register to view the recording and my slides. Thanks to everyone who attended, and especially… there’s a gap of id’s between 47000 and 50000 with no movies, but your random number generator picks values in… solution for randomly choosing rows involves some compromise, either of performance, or of accuracy of randomness. The ORDER BY RAND() solution is known…
Post: Finally. How to verify if all MySQL records were recovered
April 25, 2013 By Leave a Comment
… how many records an InnoDB page stores. The index page has a header PAGE_N_RECS – this is a number of records the page stores. Obviously it doesn’t count any deleted records. The second method to confirm how many records are… Format: COMPACT, Records list: Valid, Expected records: (200 200) Here you can see “Expected records“: 200 in the header and 200 records were found…
Post: Understanding the maximum number of columns in a MySQL table
April 8, 2013 By 5 Comments
… be two sets of polls: “What is the maximum number of columns in MySQL?” and “What is the minimum maximum number of columns in MySQL… the maximum number of columns is this: /* Hack to avoid bugs with small static rows in MySQL */ reclength=max(file->min_record_length… minimum maximum number of columns you can create? You may think that it is 255 based on the limit of the number of intervals above…
Post: How to recover table structure from InnoDB dictionary
April 22, 2013 By 4 Comments
… Recovery Tool for InnoDB you need two things: media with records(ibdata1, *.ibd, disk image, etc.) and a table structure. Indeed…, encoding, NULL/NOT NULL properties etc. `LEN` is the maximum number of bytes a field uses to store a value. I’m… CREATE TABLE statement internally they always go first in a record. The second issue we should take into account is internal…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… and establish global ordering for every transaction, and the expense of doing that for Galera is approximately one RTT between the…? Results In both of the above examples you can imagine plenty of concurrent clients attempting to modify the same record at once. But… transactions for you. However, each autocommit is retried only the number of times specified by this variable (default is 1 retry). This…
Post: Percona Server 5.5.30-30.2 rerelease fixes non-restart issue
April 24, 2013 By Leave a Comment
… in this blogpost. (Ignacio Nin) This release of Percona Server for MySQL has fixed a number of performance bugs. (Alexey Kopytov) Drop table…). The log tracker thread was unaware of the situation when the oldest untracked log records are overwritten by the new log data… fixed #710799 (Alexey Bychko). Debian packages included the old version of innotop. Fixed by removing innotop and its InnoDBParser Perl package…
Post: High-load problems? Investigate them with 'pt-query-digest'
April 23, 2013 By 2 Comments
… called pt-query-digest. One customer was suffering from periods of high load on their database server, leading to degraded application…, but at least you get a nice ranking of queries sorted by the number of times they appear in processlist. In this case… time. If you need to get started, there are good recorded webinars on the subject, and the upcoming Percona Live conference…
